open source

The open source movement supports transparency in source code. When software is used in decision making this is especially important.

free software

The first open source movement was free software. Its founder Richard Stallman proposed the copyleft or "Share Alike to everyone" as the basic model on which all instructional capital must be shared: from each according to their ability, to each according to their need - and of course ability to acquire hardware to run and skill to read or modify the software to their own needs. They likened the freedom of software to freedom of speech. Accordingly, their concerns and requirements went far beyond open source. The GPL and LGPL are source licenses, and GFDL is for open content.

extend and own the commons

In the mid-1990s an attempt to define open source independent of free software was made by Bruce Perens, who credits Chris Peterson of the Foresight Institute with the model that eventually emerged. In this model, commercial extension of the commons and even its subsequent privatization was actually allowed, as there was no Share Alike requirement. This is not surprising given that Peterson is an avid admirer of Friedrich Hayek who is the premier libertarian economics and very influential in the development of neoclassical economics, based on this same principle that the commons must be exploitable by private sector interests. This politics was apparently lost on Perens whose Debian Open Source Guidelines left loopholes open that have permitted a lot of "open source licenses" to proliferate on incompatible terms.

not Share Alike

Like free software the no restrictions on field of use and no restrictions on who may use provisions were retained. Thus the CC-by-nc-sa license, which forbids commercial use even by a commercial party who contributes to the material, is not an open source license. The Share Alike movement is a distinct thing.

not open content

There are somewhat different issues involved in fictional works and others where attribution and credential are primary concerns. These are not generally applicable to source code as it is diagnostics, not reputation, that validates source code.

Accordingly the open content movement has evolved in some different directions - see that article for more details on how.